Remote control system



Filed Dec. 17, 1943 KNK m b m b 9 b 0 w @mwm N1QN NN .1 .FNN .1 J f m HQ M WF 2M PNQNN .I I. ...|.I .NI .HH LN wm H TIH ANMTH l Wm IMJ E .N [QL 1TH IQL M W L w n \mm ml-lsv .u LlL LIL LL m1 wml@ n w NN 1mm. R NNN m ,SN

Patented May 6, 1947 REMOTE CONTROL SYSTEM yWillard l. "Place, Penn Township, .Allegheny County, Pa., assignor to 'The Union `Switch `t Signal-Company, Swissvale, Pa., a corporation of Pennsylvania Application December 17, 1943, Serial No. 514,642

y 5 Claims. l My invention relates to remote control systems, and more particularly to centralized traffic control systems for railroads for the control of railway signals or other trac controlling devices from a central point of control, such as a train v'di'spatchers cnice, and for the indication of .such devices or of train movements .at the control office.

VOne object of my invention is .the provision of a s'yste'mlof remote control suitable for the direct control'of unattended manual block signals, The system of my invention is .an improvement upon that disclosed ina copending application for Let- Jters'Patent'of the UnitedStates, Serial No. 514,- 641, iiled 'December 17, 1943, now U. S. Letters Patent 2,396,134 granted March 5, 1946, by Andrew J. Sorenson, for Remote control system.

Another object of my invention is .the provision of a .system for communicating by code between a control cnice Vand Va plurality of remote stations, in lwhich the codes comprise single impulses of alternating current within a band of frequencies which is preferably above the voice frequency range 'but suitable for transmission overexisting telephone circuits, the current lbeing modulated at different rates, and in which the modulating frequencies are applied singly or sequentially to provide code .signals of diiferent characters.

Other objects, features and purposes of my invention will be pointed out as the description proceeds.

,I 'shall describe one form .of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

Referring to the accompanying drawing, the reference characters Y and Z designate a .pair of line wires which it is to be understood provide a telephone circuit extending from a Ycon-trol cnice at which-the apparatus vat the left `of the drawing is located, througha plurality of stations situated at spaced points along -a stretch of railway at each of which stations a pair .of manual block signals LH and RH is provided, as indicated by the track diagram, `each station being :equipped with apparatus similar to that shown at the right of the drawing having .a connection to the line wires Y and Z .as shown. It may be assumed that 'the stretch is not provided with track circuits except for -a Vshort detector section at each station, each -such section having a track relay TR vfor controlling'the signals .and for indicating the movements of trains past the station, train 'fmeveme'nts through the stretch being VYgoverned 2 yprimarilyby train orders 'supplemented by Amanual control of the signals. i

The signals, identified by the references LB.' and RH, are `of the usual color light'ty-pe., arranged to display proceed, permissive or stop indications by the lighting of suitable lamps G, Y .and R, respectively, the circuits for which are controlled by a group oflstickrelays DS, LHS'and RHS.

In its specic embodiment as shown, the system of my invention provides facilities for the manual control of .such a .group of signal-control relays at leach vof live stations and for 'indicating at the oiiice the positions of relays LHS and RHS at each station. The control'apparatus atv ythe office comprises a -controlpanel foreach station, each including one of a series of push-buttons PBI to PB5. Each vbutton when pressed effects the delivery `of alternating current of a )distinctive frequency-to the line circuit to which the apparatus at the corresponding station is selectively responsive, and this vcurrent is modulated at different rates in accordance with the .positionsof .-.a pair lof lsig-nal levers such as HLI and DL! in the ycorresponding panel to selectively control vthe relays DS, -LHS and RHS at the selected station. More particularly, the Amomentary operationof one of the ve buttons PB=| `to 'PBS effects the delivery of `an impulse of modulated carrier current to the line wires Y and Z having a frequency identified as fil to fl5, respectively, which is modulated at a frequency 'identied vas f|lf2 or f3, thereby energizing the Icorresponding one of the three-relays DS, `LHS-or RHS at the Vselected station. A group of three relays Ml, vM2 and M3 :provides means VVwhereby the lcarrier current may be Amodulated at anyone of lthe three frequencies fl, ,f2-cr f3, and also'serves to apply thevfrequen'- cies fl .and f2 or fi :and f3 alternately so that relay DS `may be 'picked up along with 'relay'LI-I'S or RHS. Relays LHS fand-RHS are slow release relays which are held Vpicked 4up `by localstick `circuits controlledby the track relay TR, while relay DSis held energized by a vlocal stick circuit con;

' trolled by relay LHS vor RHS. A quick acting frelay NIP, 'which responds 'to each of the 'modulation frequencies fl, f2 and `f3 is operated byeac'h control impulse of modulated carrier current having the carrier frequency to which the "staticn is selectively responsive, and provides means for manually releasing 'the signal stick relays, and vfor energizing an indication transmitter relay Tl in response to each control impulse receved.`

The V4following table lists the relays M which 3 are energized, the modulation frequencies of the control impulses, the control relays at the selected station which are energized, and the signal lamps which are lighted in response to the control impulses, for each of the different operating po-V sitions of the signal levers HLI and DLI:

Relay TI is a slow release relay, and it is arranged to be energized momentarily when a train enters the detector track section to put the signals automatically to stop, The energization of relay TI effects the delivery of an indication impulse of modulated carrier current to the line vvires Y and Z having a frequency which is characteristic of the station, the carrier frequencies transmitted from the five different stations being identified as fl@ to f20, respectively. This current is modulated at a frequency fl if relays LHS and RHS are released and at a frequency f2 if one of these relays is energized, and serves to operate an ofce indication relay K of the stick polar type selected by the carrier frequency and controlling one of a series of lamps EI-E5 to inclicate the condition of the signals at the transmitting station. Lamp EI, for example, responds to the frequency fI6 and is lighted only when the signals at the station shown are at stop.

To generate the impulses employed for the control of the signals, an oscillator comprising an electron tube VTI is provided at the office which is arranged to generate carrier currents of different frequencies by the provision of an adjustable tuned circuit including the coil 2| and a plurality of condensers such as CI- In the drawing,

various tuned circuits are shown comprising coils,

and condensers arranged to respond selectively to particular frequencies, and to enable the operation of the system to be more readily understood, a legend indicating the frequency to which the circuit is responsive is shown adjacent the tuned circuit elements in each instance. The connections to coil 2| for example, are such that the electron tube VTI may be adjustably connected so as to generate any one of the five control frequencies fI I to fl 5. These frequencies are modulated by a second electron tube VT2 having a control circuit including a tuning coil 22 and a condenser such as C2 by means of which the tube VT2 may be adjustably connected so as to generate any one of three modulation frequencies fl, f2 or f3, which frequencies are impressed upon the input circuit for the tube VTI so as to cause periodic variations in the amplitude of the current of the carrier frequency delivered thereby. The modulated carrier currents are delivered to the line wires Y and Z through an amplifier tube VT3 and a band pass filter fI I-I5 and received through a similar filter at each station and supplied' to the input circuit of an amplifier tube VT8.

The indication impulses transmitted from each station comprise modulated carrier currents generated by electron tubes similar to those at the ofiice, these including a tube VTS for generating one of five carrier frequencies in a band IIB- 20, such as the frequency fIE, as shown, and a tube VTS;` for generating either of two modulation frequencies fl and f2. The modulated carrier current generated by these tubes is delivered to the line Wires Y and Z through an amplier tube VTi and a band pass filter fII-ZIL and supplied through a similar filter at the office to the input circuit of an amplifier tube VT4.

It is to be understood that the band pass filters fII-I and fIG-ZB are arranged to present a relatively low attenuation to currents of the designated carrier frequencies as Well as to the side band frequencies associated therewith, and that the filters fI I-I5 present a maximum attenuation to frequencies passed by the filters fIB-ZO, and vice versa.

I shall now describe the operation of the system of my invention in detail, assuming first that the operato-r moves lever HLI to its right-hand position and then presses the associated pushbutton PB I, in order to light lamp Y of signal RH at the station shown.

The lament circuits for the electron tubes at the office and at each station are normally energized by connections to the terminals B and C of a suitable low voltage source, while their plate circuits are energized from a high voltage source having the terminals BH and C. The connections for energizing the plate circuits for tubes VTI, VT2 and VTS include the contacts b of the push-buttons PB, and the closing of contact b of button PBI therefore activates the electron tubes VTI, VT2 and VTS, while the closing of contact c of button PBI completes a tuned circuit including coil 2I and a condenser CI, resonant to the frequency fI I, causing tube VTI to generate that frequency. The closing of contact a of button PBI completes a circuit from terminal B of the local low voltage source over the right-hand contact a of lever HLI, back contact c of relay MI through relay M3 to terminal C, so that relay M3 becomes energized completing a tuned circuit at its front contact b including a portion of the coil 22 and a condenser similar to C2, which circuit is resonant to the frequency f3, causing tube VT2 to generate that frequency and to modulate the carrier current of frequency fII at the corresponding rate. This modulated current is delivered to the line by the amplifier VT3 and received by the amplifier VT8 at each of the stations, where the output of the tube VT8 is supplied to a rectifier 23 through a two-stage filter tuned to a different frequency at each station, and arranged to pass only one of the carrier frequencies of the band fII-IE together with the side band frequencies corresponding to its modulation, this carrier frequency being fI I at the station shown. Rectifier 23 therefore receives the carrier current of frequency fII at the one station only, and serves as a detector or demodulator to convert its periodic variations into alternating current, which in the case being described is of frequency f3. This alternating current is supplied to three sets of tuned circuit elements which provide resonant circuits selectively responsive to the frequencies fI, f2 and f3, respectively, each comprising a condenser such as C3 and a coil 28 to which the input terminals of a rectifier 25 are connected, the output terminals of each rectifier 25 being connected to one of the relays DS, LHS and RHS, Each resonant circuit is completed through a rectifier 24 and relay MP, and through rectifier 23 and resistor 29, in parallel. Since the frequency supplied is f3, it will be seen that relay RHS becomes energized through rectifier 25, and relay MP through rectifier 24, due to the resonant response of the circuit elements tuned to that frequency.

When button PB-l is released to terminate ythe .control impulse, relay MP releases quickly, completing a stick circuit for relay -RHS extending from terminal B at front contact a-of relay TR, vback contact a Yof relay MP, and the front 'con-- tact a and Winding of relay RHS to terminal'C, so that relay RHS remains picked up lighting lamp Y and extinguishing lamp R of signal RH by the operation of its contacts c and b.

When relay MP picks up, the closing of its con-- Atact b energizes relay Tl which vcloses its contact a and thereby connects terminal BH of the high voltage source at the station to the plate circuits for tubes VTS, VTG and VT?. Tube VT is adjustably connected to generate carrier current f frequency fili only, modulated by tube VTS, 4and when relay RHS picks up its contact f shi-its the connections uo coil 26 to change the modulation frequency from fl to f2, consequently current Vof frequency Fit generated by tube VT and modulated at the frequency F2 by the electron tube VTS is supplied to the line until relay Tl releases, following the release of relay MP. At the ofce, this current is received by the amplier tube VT4 and supplied to ve similar sets of selective circuit elements, of which but two are shown, each responsive to a different one of the five frequencies JIS to Jl, to each of which is connected a demodulator El' for supplying current of frequency fi or f2 to tWo tuned circuits selectively responsive to these frequencies and similar to Ythose controlling relays DS and LI-IS but arranged to operate a polar stick relay such as the relay KI to its normal or reverse position. In the case being described, the carrier frequency is fi and the modulation frequency is f2, and consequently relay Ki reverses to extinguish lamp El, thereby indicating the response of relay RHS to the operation of button PBG- I shall next assume that the operator moves lever DLI to the right, leaving lever I-I-Liv in its right-hand position, and then presses button PB l, in order to light lamp G of signal RH at the stationshown.

In response to the operation of button PBi, relay MS becomes energized and the electron tubes VTi, VT2 and VTS become activated to deliver current of frequency fil modulated at the free quen-cy f3 to the line, as the preceding example, and in addition, a circuit is completed from terminal B at contact a of button PBI over the right-hand contact c of lever HL, front contact a of relay M3 and the right-hand contact a of lever DL through relay Ml to terminal C, so that relay Mi picks up. The opening of back contact c of relay Ml deenergized relay M3, which therefore releases after a brief period, the dropping of its contacts a and b opern'ng the circuit for relay Ml and changing the modulation frequency to .fl by completing the tuned circuit inciuding baci; contacts b or" relay M3 and M2 and front contact b of relay M i. Relay M l releases after a brief period, and by closing its back contact c, reenergizes relay M3 which operations change the modulation frequency from fi to f3. Relay M3 reenergizes relay Ml again, these op-1 erations continuing' as long es button PBI is held pressed, so that the carrier current is modulated alternately and repeatedly by the frequencies fl and f3, at a rate sufficient to maintain relay RHS picked up and valso energizing relay DS to complete its stick circuit extending to terminal B at the front contact d of relay RHS.

Consequently, when button VPBI :is released, Vre lays RHS and DS remain energized to light lamp G of signal RH. The resultant indication impulse 'is similarto that previously described and consequently lamp El remains dark.

Signal LH may be similarly caused to display its permissive indication by operating lever HL! to the left, with lever DLE in'its normal left-hand position, in which case the modulation frequency is f2 instead of f3, while if lever DL'i is in 'its reversed or righthand position, the frequencies fl and f2 are applied -alternately by the operation of relays Mi and M2 to pick up relay DS along with relay LHS, therebycausing signal LH Ato indicate proceed.

I shall next assume that after signal LH or RH has been cleared, vthat the operator restores the signal levers -to their normal positions as shown in the dra-Wing, and then presses button PB'i to put the cleared signal to stop. Relay Mi picks up, causing the frequency fi i delivered to `the Aline in response to the operation of button PB! to be vmodulated by the frequency fl, thereby energizing relays DS and MP. The opening of conn tact a of relay MP releases relay LHS or RHS, thereby putt-ing the signal to stop and opening the stick circuit for relay DS, so that when the impulse is terminated, relay DS releases along with relay MP. An indication impulse of frequency -fl is transmitted to the office as in the preceding example, but in this case it is modulated yby the frequency fl, because relays LHS and R--IS are both in their released positions, thereby energizing relay Ki in the normal direction to light lamp El to indicate that the `previously cleared signal has been restored to stop.

When a train venters the detector tracl; section to release relay TR, with signal LH or dis" playing its permissive or clear indication, relay LHS or RHS is deenergized to restore the signal automatically to stop, due to the opening of front Contact a of relay TR, but before the relay LHS or RHS releases, a circuit is closed momentarily from terminal B over back Contact a of relay TR and front contact e of relay LHS or RHS to pick up relay Ti, causing the transmission of an indication impulse which will be modulated by the frequency fl when both relays LHS and RHS are in their released positions, to light lamp El, as in Ithe preceding example, thereby indicating the movement of the train into the detector section and the return of the signal to stop.

If a diierent station selecting push-button, such as the button PBS, is operated, similar operations will be effected at another station at which the apparatus is responsive to another carrier frequency, such as H5, the resulting indication impulse also having a different carrier frequency, such as i253, to control an indication relay K5, as will be readily understood.

It may happen that a control impulse is being transmitted to one station, and an indication impulse received from that station at the time a train enters the detector track section at another station and initiates the transmission of another indication impulse. No interference will occur, and the various indication relays Kl to K5 may be operated simultaneously due to the provision of communication channels between the office and dilerent stations which are selectively responsive to different carrier frequencies as described.

Although I have herein shown and described only one form of remote control apparatus em- 7 bodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a remote control system, an oce and a station connected by line wires, manually controllable means for at times impressing carrier current of a given carrier frequency on the line wires and for selectively modulating said current by different modulation frequencies, means at the station for selectively receiving said current including selective circuit elements resonant to the carrier frequency, demodulating means for converting said current to alternating current of the modulation frequency, a group of slow release control relays at said station, circuits for selectively controlling said relays by the alternating current supplied by said demodulating means, the circuit for each control relay including a rectifier and selective circuit elements resonant to a different one of said modulation frequencies, a quick release relay, an energizing circuit for said quick release relay including a rectifier interposed in the circuits by which said demodulating means supplies current to said selective circuit elements, and rendering such relay responsive to current of any of said modulation frequencies, a holding circuit for each control relay including its own front contact and a back contact of said quick release relay, a slow release transmitter relay controlled by a front contact of said quick release relay, means controlled by said transmitter relay when energized for irnpressing carrier current of a second carrier frequency on the line wires and for modulating such current by different modulation frequencies in accordance with the condition of said control relays, means at the office for selectively receiving said second carrier current including selective circuit elements resonant thereto, demodulating means for converting said second carrier current to alternating current of the modulation frequency, and an indication relay controlled thereby for indicating the condition of said control relays.

2. In a remote control system, a slow release stick relay and a second stick relay, a plurality of control circuits governed jointly by said relays, pick-up circuits for said relays including rectiers supplied with current through resonant circuit elements to render each relay responsive to alternating current of a different frequency, quick acting relay connected through a rectifier to said resonant circuit elements to render such relay responsive to current of each of said different frequencies, holding circuits for said stick relays including their own front contacts, that for the slow release relay including a back contact of said quick acting relay and that for the second stick relay including a front contact of said slow release relay, means for supplying an impulse of alternating current of one of said frequencies or the other to said selective circuit elements whereby the slow release relay is picked up to be held energized upon the release of said quick acting relay or is released in response to the operation of said quick acting relay, and means for supplying impulses of the different frequencies to said circuit elements in quick succession whereby the stick circuit for the second stick relay is completed and both stick relays are 8 held energized upon the release of said quick acting relay.

3. In a remote control system, three stick relays, two of which are slow to release, a plurality of control circuits governed jointly by said relays, pick-up circuits for said relays including rectifiers supplied with current through resonant circuit elements to render each relay responsive to alternating current of a different one of three frequencies, a quick acting relay connected through a rectifier to said resonant circuit elements to render such relay responsive to current of any one of said three frequencies, holding circuits for the two slow release stick relays including a back contact of said quick acting relay, a holding cir.. cuit for the third stick relay including front contacts of said two slow release stick relays connected in parallel, means for supplying impulses of alternating current of said three different frequencies to said resonant circuit elements one frequency at a time whereby one slow release relay or the other is picked up to be held energized upon the release of said quick acting relay or is released by the operation of said quick acting relay, and means for supplying impulsesl of two frequencies to said circuit elements in quick succession whereby the stick circuit for said third stick relay is completed to hold such relay energized along with one or the other of said slow release relays following the release of said quick acting relay.

4. In a remote control system, an office and a plurality of stations connected by line wires, a controllable device and a locally controlled relay at each station, a stick relay at each station for governing the controllable device at such station, a stick circuit for each stick relay including a front contact of the associated locally controlled relay, manually operable means at the office for controlling said stick relay, transmitting means at each station responsive to the release of the locally controlled relay for impressing upon the line wires an impulse of alternating carrier current, the transmitting means at different stations being adapted to transmit impulses of different carrier frequencies, means at each station for modulating the carrier current impressed upon the line wires by the associated transmitting means by one frequency or another dependent upon the position of the associated stick relay, indication means at the office for indicating the positions of said stick relays, and circuits for controlling said indication means including selective circuit elements resonant to each of said carrier frequencies and other selective circuit elements resonant to each of said modulation frequencies.

5. In a remote control system, an oiiice and a station connected by line wires, means at the oice for impressing alternating carrier current on the line wires, means for modulating said current at one or another selected frequency, control means for selecting the modulation frequency, means at the station for selectively receiving said current including selective circuit elements resonant to the carrier frequency together with means for converting said current to alternating current of the modulation frequency, a slow release stick relay, a second stick relay, a quick acting relay, and control means controlled jointly by said stick relays, all located at the station, a circuit for controlling each stick relay and said quick acting relay by said alternating current each said circuit including a rectifier and selective circuit elements resonant to an impulse of a dierent modulation frequency whereby each stick relay may be operated along with said quick acting relay without operating the other, a holding circuit for said slow acting stick relay governed by a back contact of said quick acting relay to maintain the slow acting relay energized following the reception of an impulse of a given frequency and to release such relay upon the reception of an impulse of a different frequency, a holding circuit for said second stick relay including a front contact of said slow acting relay, and means for operating said control means periodically to supply impulses of two modulation frequencies alternately and repeatedly and thereby operate said second stick relay Without releasing said slow acting relay.

WILLARD P. PLACE.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number 10 UNITED STATES PATENTS Name Date Boswau Apr. 30, 1940 Hart Sept. 9, 1941 Seeley June 9, 1942 Seeley June 17, 1941 Boswau Aug. 3, 1943 Clausen Jan. 29, 1918 Bruckel July 14, 1936 Blodgett Apr. 5, 1938 Snavely May 17, 1938 Preston May 23, 1939 Lewis Oct. 21, 1941 Van Horn Mar. 16, 1943 Baughman Oct. 26, 1943 From Dec. 1, 1925 FOREIGN PATENTS Country Date British Aug. 2, 1917 

